This invention relates generally to devices containing an electroconductive liquid such as mercury for automatically disabling the electrical circuit and/or ignition circuit of a motor vehicle upon the occurrence of an accident so as to prevent a fire caused by electrical sparks which ignite spilled fuel. More specifically, this invention relates to such devices which are actuated both by a tilting of the vehicle through at least a minimum predetermined angle with the horizontal or by an impact force applied to the vehicle.
Broadly speaking, devices which contain an electroconductive liquid such as mercury for automatically disabling the electrical circuit of a motor vehicle upon the occurrence of an accident have long been known in the prior art. For example, see U.S. Pat. Nos. 1,861,800 issued to M. P. Janisch on Jun. 7, 1932; 2,192,262 issued to C. A. Griesedieck on Mar. 5, 1940; 2,208,179 issued to F. Colby on Jul. 16, 1940; 2,509,514 issued to S. R. Matthews, et al. on May 30, 1950; and 3,034,097 issued to J. B. English et al. on May 8, 1962. All of these patents involve motor vehicle electrical system or ignition system disconnect switches which operate upon a tilt of the vehicles in which the switches are mounted beyond a predetermined minimum angle with the horizontal as, for example, when such vehicles turn on their sides or turn upside down.
Other tilt type safety disconnect switches for motor vehicles known in the prior art do not involve the use of an electroconductive liquid. See, for example, U.S. Pat. Nos. 4,221,278 issued to F. Ponzo on Sep. 9, 1980; 3,889,774 issued to G. B. Schwenk on Jun. 17, 1975; and 3,599,745 issued to B. F. Hughes on Aug. 17, 1971. The patent to Ponzo discloses such a device which is particularly adapted to use on a motorcycle.
There are also vehicle electrical system disconnect switches known in the prior art which operate upon the occurrence of a vehicle decelerating impact force. See, for example, U.S. Pat. No. 3,509,894 issued to J. F. Brooke on May 5, 1970 which involves inertial actuation of an eccentrically distributed mass of a rotary member.
One problem which has existed in the prior art is that none of these disconnect switches are operational both by reason of a severe tilting of a motor vehicle and by reason of a decelerating impact force being applied to the vehicle. These prior art switches either operate upon the happening of one or the other of these events, but not both. Also, none of the inertially actuated prior art switches utilizes a linearly movable sliding mass or block.
By means of our invention, this and other difficulties encountered with prior art motor vehicle electrical system disconnect switches are substantially overcome.